Pasteurizing system



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R E OLSON ETAL PASTEURIZING sYs'rm madam. 9, 1948 Sept. 19, 1 950 Patented Sept. 19, 1950 I 2,522,796

orlcE Raymond E. Olson, Pittsford, and George E. Heller, Rochester, N. Y., assignors to Taylor Instrument Companies, Rochester, N. Y., a corporation of New York Application January 9,. 1948, Serial No. 1,8"

7 Claims. (Cl. 257-2) 1 2 This invention relates to a method of and to tion will appear from the detailed description apparatus for pasteurizing a liquid in a so-called and claim when taking the drawings in which: short-time pasteurizer. Fig. 1 is a diagrammatic showing of a pas- For example, in the pasteurization of milk, the teurizing system of the present invention and U. S. Public Health Service code requires that 5 with which the method of this invention can be every particle of milk shall remain in the holdpractised;

ing tube for a period of not less than fifteen Figs. 2 and 2A are respectively a longitudinal seconds and that the temperature shall be not section and a transverse section oi a modified less than 160 degrees F. form of velocity sensing device; and

In the past, in the short-time pasteurization of Fig. 3 is a modified form of the system shown milk or the like, the holding tube communicates in Fig. l.

with the inlet of a flow diversion valve which is In the system disclosed in Fig. 1, there is inprovided with a forward flow discharge port and cluded a combined heater unit I and a regenerata diverting discharge port. Thermosensitive ing unit 6. In the heater unit the milk or other means responsive to the temperature of the milk liquid to be pasteurized flows through a set 0! in the holding tube is effective to position the coils or plates 1 in heat exchange relation to a flow diversion valve so that while the milk is at set of heating coils or plates 8 through which or above the predetermined temperature, the inlet there is recirculated water maintained at a temof the valve communicates with the forward flow Derature slightly above the pasteurizing temperadischarge port from which the milk passes to a ture. Th r n r ting unit 8 includes two bottling machine or the like. However, if the passageways 8 and I0 in heat exchange relation temperature of the milk drops below the predeto eachother. The raw milk from the tank ll termined value, the inlet port of the flow diveris pumped by a pump I! through passageway 8 sion valve is connected to the diverting discharge of the regenerator and thence through passageport so that the milk can be repasteurized until way I of the heater. It will be understood that itstemperature is at the required value. In such the pump i2 is driven'by an ui a le Co stant a short-time pasteurizing system, it is intended speed mo o 3; e m l eav n the heater that the milk be pumped through the holding passageway 1 pa ses in o a s ta o d n tube tube at such a speed'that it takes each particle 94. through which themflk travels at such a of milk fifteen seconds to pass therethrough. In spe d tha ach r v lin particle of milk is in accordance with the conventional practice, public the holding tu Period 0! fifteen eco ds. health authorities adjust the speed of the motor The holding tube discharges through the p that drives the pump. This motor, when thus 2| into the inlet port of a flow diversion valve adjusted, is locked so that it cannot be tampered FD of a construction similar to that disclosed in with. On rare occasions, the speed of the motor the patent of R. E. Olson, 2,47 ,984, granted June and consequently the speed of the pump can 14. 1949. deviate from the required value. If the speed of If the milk is above the required temperature, the pump increases, it will be appreciated that a the how diversion valve will have its movable porparticle of milk will pass through the holding tion in the reverse position from that shown in tube in less than the specified fifteen seconds so Fig. 1. s ha the inlet Dori; mm nic t s with that proper pasteurization is not effected. the forward flow discharge port i5 of this valve. In accordance with the present invention, when Fromthe forward flow port, the pasteurized milk the velocity of the milk passing through the holdflows through pipe to and through passageway ing tube exceeds a predetermined value, the milk ill of the regenerator. This regenerator conducts from the holding tube is prevented from reaching the pasteurized milk from the holding tube, in the bottling machine until such time as each parheat exchange relation to the raw milk in the ticle of milk traverses the holding tube in not passageway 9, thereby serving to cool the pasless than fifteen seconds. teurized milk and to heat partially the incoming In accordance with another feature of the inmilk. The pasteurized milk from the passagevention, the flow diversion valve is a short-time way 9 flows through cooler I1 and through pipe pasteurizing system is operated to its diverting It to a bottling machine or the like (not shown).

position in response alternatively either to a drop If, however, the milk in the holding tube II in temperature of or to the increased velocity of has not been heated to the proper temperature, the milk passing through the holding tube. the flow diversion valve FD will position its mov- Various features and advantages of the invenas able portion as shown in Fig. 1 so that the inlet portion of this valve communicates with the diverting discharge port It. Under this positioning of the flow diversion valve, the improperly pasteurized milk will flow through passageway into the tank H so that this milk can be reprocessed.

The temperature of the pasteurized milk is preferably sensed near the discharge end of the holding tube i4. As herein illustrated, the temperature of this milk is sensed by a thermoelectrical device, which comprises a tube system including a bulb 22 subjected to the temperature of the pasteurized milk, the bulb communicating through capillary tube 23 with a Bourdon spring 24. The bulb as well as the capillary tube and the Bourdon spring are filled with a thermosensitive medium in accordance with the wellknown practice. The movable end of the Bourdon spring actuates a link 25 which swings a pivoted arm 26 between a low-temperature contact 21 and a high-temperature contact 28. The pivoted arm .26 and the fixed contacts 2'? and 28 constitute an electrical switch. This switch governs electric circuits (to be described) or the solenoid 29 to position the movable element 30 of an electro-pneumatic valve so that when proper pasteurizing conditions prevail, this mov able element will be moved to the alternate position from that shown in Fig. 1. Thus the air supply pipe 23 is connected to the pipe 3% com municating with the diaphragm motor 35 of the flow diversion valve. This diaphragm motor, when thus supplied with compressed air, moves the movable portion of the flow diversion valve to its alternate position from that shown, so that the pasteurized milk passes through the forward flow discharge port i5 and through pipe iii as well as the remainder of the system as previously mentioned,

In accordance with the present invention, provision is also made for preventing the discharge of milk. to the discharge port id, in the event that each particle of pasteurized mill: fails to remain. in the holding tube for at least fifteen seconds. Various means can be utilized to sense the condition that the milk has traveled through the holding tube for less than the prescribed pe= riod of time. As shown in Fig. i, this sensing means comprises a diilerental switch mechanism 8. In connection with this mechanism, an oridoe plate 38 is introduced into pipe ti. At each side of the orifice pipe there are provided branch pipes 38 and 4d The end oi the pipe all is closed by a flexible diaphragm ti while the end of branch pipe 39 is closed by a flexible diaphragm 62. These two diaphragms, which are in alinement, are connected by an arm at. The arm 33 carries the bracket M to control the switch contact 45. The arrangement is such that with the proper flow of milk through the orifice in plate 38, the differential pressure applied to the diaphragms 4i and 42 will be such that the switch contact 45) will be open, whereas, if the rate of flow increases abnormally, the pressure on these diaphragms will be such that "the switch contacts 65 will be closed; The closure of the contacts as are effective in the arrangement shown in Fig. l, to interrupt the circuit to be described of pump motor l3 so that the pump will stop advancing milk through the holding tube.

The operation of the circuits shown in Fig. i will first be described under the assumed conditions that the milk in the holding tube is at the required temperature and that each particle of milk is moving at such a velocity that it requires all! lit

fifteen seconds for it to travel through the holding tube. The operation of the circuit under abnormal conditions will then be described.

With the temperature of the milk at the prescribed value, the pivoted arm 26 will be in engagement with the high-temperature contact 28 of the switch. Under this condition, a circuit will be completed from one side of the current source, the supply conductor 41, resistor 48, switch contact 28, pivoted arm 26, conductor 49, winding of the relay 50, supply conductor 5| to the other side of the current source. Under the control of this circuit, the relay is energized and locks itself in this condition, in a circuit now traceable over conductor 41, resistor 48, armature 53, and front contacts, as well as the winding of the relay 50, to the supply conductor 5i. Relay 50 is thus locked energized until the pivoted arm 26 is swung into engagement with the contact 2'! whenever the temperature of the milk drops below the prescribed temperature. With the pivoted arm 26 in engagement with the contact 21, the winding of the relay 50, is short-circuited by a circuit traceable from one side of the current source, conductor 41, resistor 48, armature 53 and front contacts of relay 50, conductor 49, arm 26, and contact 21, conductor 5| to the other side of the current source. It will be understood that the resistance of the winding of the relay 50 is such that it will not remain energized when in multiple with the resistance of the resistor 48.

With the relay 50 energized, the relay 6A is operated in a circuit including supply conductor ti, winding of relay 5d, armature 5d and front contact of relay 5t, conductor 56 to the other current supply conductor 5i. When relay 54 is.

thus energized, it closes a circuit for operating solenoid 29 of the electro-pneumatic valve 3i. This circuit may be described as extending from the current supply conductor El, conductor I2, winding of solenoid 29, conductor 13, front contact and armature ll of relay St, to the current supply conductor 5i. Solenoid 29 operates the valve ii to supply compressed air to the dia= phragm motor of the flow diversion valve. This adjusts the flow diversion valve to its forward flow position. With the flow diversion valve in its forward fiow position, the switch 59 will be moved to its right-hand position in which the green lamp G is lighted. The lighting circuit extends from the current supply conductor tl,

lamp G, conductor 41a, switch 59, conductor Sla, to the supply conductor St. The green light indicates to the operator that the flow diversion valve is in its forward flow position.

Since it has been assumed that the milk is flowing normally through the holding tube, the switch s will have its contacts 45 opened so that the relay 5B is deenergized at this time. Under this condition and with the relay 50 energized a circuit is completed for the relay 60 which closes the operating circuit of the motor IS. The circult for the relay 60 extends over supply conductor 47, push button 6i, back contacts and armature 62 of relay 58, conductor 63, winding of the relay Bil, conductor 64, armature 65 and front contact of relay 54. conductor 5! to the other side of the current source. As long as this circuit is completed, the motor I3 will operate the pump l2 to advance the milk through the holding tube It. In the event that the operator desires at any time to stop the pump this is effected by depressing the push button 61 to interrupt the operating circuit of the relay 6G. The

deenergize. The release of relay relay to in turn releases tointerrupt the operating circuit of the motor i3.

If, however, the temperature of the milk drops below the pasteurizing value, pivoted arm 28 will be moved into engagement with the low temperature contact 21. This is effective to deenergize the relay 50. Relay 50, at its armature BI and front contact, opens the operating circuit of the relay 54 which deenergizes. Relay 54, at its armature 'iLinterrupts the operating circuit of the solenoid 29. This circuit, it will be recalled. extended from the current source over conductor 47, conductor i2, winding of the solenoid 29, conductor 13, front contact and armature ll of the relay 54, conductor ii to the other side of the current source. When the solenoid 29 is thus deenergized in response to the interruption of its circuit as Just described, the movable part of the electro-pneumatic valve 3| moves to the position shown in Fig.

off from the pipe 34 so that the flow diversion valve FD moves to the position shown in Fig. 1.

In this position the improperly pasteurized milk is diverted through the diversion port it and pipe 20 back to the milk tanks.

Let it be assumed that the temperature of the milk is at the proper value, but the flow of the milk through the holding tube I4 is hurried. Under this condition, the pivoted arm 26 will remain in engagement with the high temperature contact 28 so that the relays l0, 54,-and the solenoid 29 will remaincnergiz'ed. Under this condition, the flow diversion valve will be in its forward flow position so that the milk will tend to flow through the forward flow discharge port l and the pipe I through the remainder of the 1 wherein the compressed air is out system as previously described. However, since the milk is traveling at an improper velocity through the holding tube, the differential pressure switch S will have its contacts closed. In response to the closure of these contacts, the relay 58 will be energized. This circuit is traceable from one side of the current source, conductor W, winding of the relay 58, conductor 61, switch contacts now closed, conductors 68 and M to the other side of the current source. The relay 5B is energized in this circuit and its armature t2 and front contact interrupts the operating circuit of the relay 80 causing it to interrupts the operating circuit of the motor l3 to stop pump 02. It will be noted that the relay on, when thus operated locks itself in this condition in a circuit traceable from one side 01' the current source, conductor 5|, push button 69, armature $2, I

so, conductor 41 to the other side of the current source Thus the relay 68 will be locked energized until the operator depresses the push button 69. Thus the motor l3 and its pump l2 can not be started until the operator pushes the button 69 which will take place after the abnormal operating conditions have been corrected.

In Figs. 2 and 2A there is indicated a modified form of switch for lindicating the abnormal passage of milk throug the holding tube II. In this modification, a. rigid blade 15 extends into the pipe l2. This blade is: mounted on a flexible diaphragm 16 which is sealed in an opening at the upper side of the pipe 2|. The blade II at its upper end actuates the movable element otthe switch contacts 45 to close the switch whenever the velocity of the milk passing through the pipe 2| swings the blade I! in a counterclockwise B0, in turn, I

front contact and winding of relay 6 described switch can be substituted for the switch S in the system shown in Fig. 1 without changing the operation of that system as described.

valve FD is moved to its diverting position so that the. milk can be diverted into the tank Ii. Also in this arrangement the flow diversion valve moves to its diverting positionwhenever the temperature of the milk drops below the prescribed value. Otherwise expressed, in this arrangement the flow diversion valve is moved to its diverting position alternatively in response to an abnormal temperature of the milk and to an abnormal velocity of the milk passing through the holding tube. In this arrangement when the temperature is above the holding value the pivoted arm 26 will be positioned in engagement with the high temperature contact 28 so that relay Bil is energized as previously described. In response to the operation of the relay 50, the relay 54 is nergized also as previously described. Relay 4 at its armature H and front contact closes a break point in the operating circuit of the solenoid 2! of the electro-pneumatic valve. If the velocity of the milk passing through the holding tube is at the proper value, the switch contacts 415 will be open so that relay its armature and back contacts, the remaining break point in the operating circuit of solenoid 29. The solenoid 29 will then be operated to apply compressed air through valve 3|, to the flow diversion valve FD so that it will be held in its forward flow position.

Let it be assumed, however, the the flow of milk is abnormal in the holding tube as a result of which the switch contact 45 will be closed. As a result of the closure of these contacts, the relay l8 will be energized in a circuit extending from the current source, conductor 41, winding of the .relay 18, contacts 45 now closed, conductors 67 and 5| to the other side of the current source. The relay I8 is energized in this circuit and at its armature Ma and back contact, it opens the operating circuit of the solenoid 29 which causes the flow diversion valve to be operated to its diverted position. As soon as the relay i8 is energized it closes a locking circuit for itself from the current source, conductor 41, winding of relay l8, armature 18a and front contacts of this relay, push button 80, conductors BI and 5| to the other side of the current source. Relay 18 will remain operated until its locking circuit is interrupted by the operator on the depression of the push button 80 when the abnormal conditions have been corrected. In this modification the operating circuits of the motor I3 is maintained complete by the relay to at the will of the operator. The circuit of the relay 60 is completed from the current source, conductor 41, push button 6|, winding of the relay 60 through the double throw switch 85, conductor 64, armature and front contact of relay 54, conductor 5| to the other side of the current source.

direction. It will be understood that this last move the flow diversion valve FD to its diverting i8 is deenergized to close at position when the velocity of the milk through the holding tube is abnormal, the double throw switch 85 is moved frm the position shown in Fig 3 into engagement with the contact 86. Otherwise the operation of this circuit will be as already described.

What we claim is:

1. In a pasteurizing system, means for heating the liquid to be pasteurized to a predetermined temperature value, a tube of a given length through which the heated liquid flows, a pump for normally advancing the liquid through said tube at a given uniform velocity, a flow diversion valve having an inlet port into which said tube discharges, said valve having a forward flow discharge port and a diverting discharge port either of which ports is connectible to said inlet port, a thermally operated electrical switch actuated in response to a drop in temperature of the liquid below said given value, a velocity operated electrical switch actuated in response to a velocity of the liquid in excess of said given velocity value, electrically operated means for connecting said inlet port to said diverting discharge port, and an operating circuit for said electrical means interrupted in response to the actuation of either of said switches.

2. In a pasteurizing system, means for heating the liquid to be pasteurized to a predetermined temperature value, a tube of a given length through which the heated liquid flows, a. pump for advancing the liquid through said tube at a given uniform velocity, a flow diversion valve having an inlet port into which said tube discharges, said valve having a forward flow discharge port and a diverting discharge port either of which ports is connectible to said inlet port, a thermally operated switch actuated in response to a drop in temperature of the liquid below said given value, a velocity operated switch actuated in response to an increase in the velocity of the liquid in excess of said given velocity value, electrical means for connecting said inlet port to said diverting discharge port, and an operating circuit for said electrical means controlled by said switches.

3 In a pasteurizing system, means for heating the liquid to be pasteurized to a predetermined temperature value, a tube of a given length through which the heated liquid flows, a pump for advancing the liquid through said tube at a given uniform velocity, a motor for operating said pump, a flow diversion valve having an inlet port into which said tube discharges, said valve having a forward flow discharge port and a diverting discharge port either of which ports is connectible to said inlet port, a thermally oper ated switch actuated in response to a drop in temperature of the liquid below said given value, a velocity operated switch actuated in response to an increase in the velocity of the liquid in ex cess of said given velocity value, electrically operated means for connecting said inlet port to said diverting discharge port, an operating circuit for said electrical means controlled by said thermal switch, and an operating circuit for said motor controlled by said velocity operated switch.

60 Number 4. The method of pasteurizing a liquid which comprises heating the liquid to a given pasteurizing temperature, pumping the liquid at the given temperature and normally at a given uniform rate of flow through a region of a given length, to a primary path, sensing any increase in the rate of flow of the liquid in excess of said uniform rate, and diverting the flow of the liquid from said region to a secondary path as soon as there is a sensed increase in the rate of flow of the liquid through said region due to improper pumping.

5. The method of pasteurizing a liquid which comprises heating the liquid to a given pasteurizing temperature, advancing the liquid normally at a given uniform rate of flow through a region of a given length to a primary path, diverting the flow of the liquid from said region to a secondary path as soon as the liquid is advanced through said region at a rate of fiow in. excess of the given rate, and continuing the diversion of the liquid to said secondary path at the will of the operator.

6. In a pasteurizing system, means for heating a liquid to be pasteurized, a tube of a given length through which the heated liquid flows, a pump for normally advancing the liquid through said tube at a given uniform velocity, a flow diversion valve having an inlet port with which said tube communicates, said valve having a forward fiow discharge port and a diverting discharge port, alternatively connectible to said inlet port, and means responsive to an increase in the velocity of the liquid flow through said tube for connecting said inlet port to said diverting discharge port.

'3'. In a pasteurizing system, means for heating the liquid to be pasteurized to a predetermined temperature value, a tube of a given length through which the heated liquid flows, a pump for normally advancing the liquid through said tube at a given uniform velocity, a flow diversion. valve having an inlet port into which said tube discharges, said valve having a forward flow discharge port and a diverting discharge port alternatively connectible to said inlet port, and means responsive individually to a decrease in the temperature of said liquid and to an increase in the velocity of the liquid flowing through said tube for connecting said inlet port to said divert ing discharge port.

RAYMOND E, OLSON. GEORGE E. HELLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Detwiler Mar. 25, 1941 OTHER REFERENCES Chemical Engineers Handbook, 2nd ed., published by McGraw-Hill Book 00., New York 19%, pages 2245 and 2264. 

